From Sahih Bukhari (Hadith 1529):
Narrated Ibn `Abbas:The Prophet (ﷺ) fixed Dhul-Hulaifa as the Miqat for the people of Medina, Al-Juhfa, for the people of Sham, Yalamlam for the people of Yemen, and Qarn for the people of Najd. And these Mawaqit are for those living at those very places, and besides them for those who come through those places with the intention of performing Hajj and Umra; and whoever is living inside these places can assume Ihram from his own dwelling place, and the people of Mecca can assume Ihram from Mecca
Reference: Bukhari 1529